Continuous transmission, especially for automobile vehicles

ABSTRACT

A continuous power transmission device provided between a movement take-off and a receiving shaft, especially for automobile vehicles, comprising a reversible continuous speedvarying device and a planetary train with four elements, in which two elements of said train are continuously active, one of said elements being coupled to the movement take-off through the intermediary of said reversible continuous speed-varying device and the other element being coupled to said shaft, each of the two remaining elements, known as change-over elements being adapted to be rendered active or passive, and further comprising means for rendering one of said change-over elements active while the other element is passive, and vice versa.

0 United States Patent [151 3,667,32 1 Maurice 1 June 6, 1972 54]CONTINUOUS TRANSMISSION, 3,433,095 3/1969 ESPECIALLY FOR AUTOMOBILE 3233,289 12/1333 VEHICLES 3,503,278 3/1970 Livezey ..74/720.5 X [72]Inventor: Jean Maurice, Paris, France FOREIGN PATENTS OR APPLICATIONS[73] Assignee: Societe Anonyme Francaise du Ferodo,

Paris, France 938,066 3/1948 France ..74/687 [22] F g- 1969 PrimaryExaminerArthur I. McKeon Assistant Examiner-Thomas C. Perry [21] Appl'848,310 AttorneyYoung&Thompson [30] Foreign Application Priority Data[57] ABSTRACT Aug. 29, 1968 France 164477 A c ntin ous powertransmission device provided between a movement take-off and a receivingshaft, especially for au- 52 us. Cl ..74/682, 74/687 tomobile vehicles,Comprising a reversible continuous Speed- [SI] 1 47 0 varying device anda planetary train with four elements, in 58 1 Field of Search ..74/682,686, 687, 689, 691, which two elements of Said train are continuouslyactive, one 74/681, 633, 690 of said elements being coupled to themovement take-off through the intermediary of said reversible continuousspeed- [56] References cued varying device and the other element beingcoupled to said shaft, each of the two remaining elements, known aschange- UNITED STATES PATENTS over elements being adapted to be renderedactive or passive, and further comprising means for rendering one ofsaid 3,340,749 9/l967 Magg el al. ..74/689 change over elements activewhile the other element is p 3,357,225 12/1967 Grube ..74/675 X Siva,and vice versa 3,426,621 2/1969 Mooney, Jr. et a1. ..74/720.5 3,427,8992/1969 Gunderson et al ..74/687 7 Claims, 7 Drawing Figures PATENTEDJUH6 I972 FIG.2

FIGS

CONTINUOUS TRANSMTSSION, ESPECIALLY FOR AUTOMOBILE VEHICLES Continuousreversible speed-changing devices, for example of the mechanical typewith extensible pulleys and belts, or of the hydraulic type with twopump/motor units, or electrical, etc., make it possible to establish aratio of speed and a ratio of torque which are continuously variablebetween a first and a second shafts, with transmission in eitherdirection, that is to say from the first shaft to the second or viceversa.

Devices of this kind are of considerable advantage in numerousapplications, and in particular in the application to automobilevehicles but, unless they are over-dimensioned, the range of operation,forward and/or reverse, over which they are utilizable with acceptableefficiency and life, is relatively narrow.

It has already been proposed to associate a planetary gear with acontinuous speed-changing gear in order to improve its conditions ofworking.

The present invention relates to a continuous transmission system,especially for automobile vehicles, comprising the association of acontinuous reversible speed-changing gear with a planetary gear trainwith four elements of the family to which belong, amongst others, anassembly of two simple planetary portions which each have a planetwheel, a crownwheel and a satellite carrier, and which are coupledtogether in a symmetrical manner by fixing the satellite carrier of onerigidly to the crown-wheel of the other, and vice versa.

To give an idea, the above-mentioned family comprises, in addition tosuch a train with two simple planetary portions coupled together: thetrains having two sets of satellites engaging with each other, in whicha planet-wheel engages with a set of satellites, another planet-wheeland a crown-wheel engage with the other set of satellites, and asatellite carrier carries the two sets of satellites. The gear trainscomprising three conical planet-wheels and a satellite carrier havingdouble satellites with conical pinions, of which one engages with two ofthe lanet-wheels while the other engages with the third planetwheel; thegear trains comprising three planet-wheels and a satellite carrierhaving triple satellites engaging respectively with the threeplanet-wheels, etc.

This family of planetary trains of four elements is hereinafter termedfamily of the kind described" and it is said that an element of thetrain is in the "active" condition when it is coupled to a memberexternal to the train, having a driving or resistant torque (in thelimit, a fixed abutment), and it is said that an element of the train isin the passive" condition when it is disconnected from any memberexternal to the train, that is to say when it is left free.

In general, in known transmissions comprising the association of acontinuous speed-varying device and a planetary gear train with fourelements, one of the elements of the train is continuously coupled to amovement take-off, for example a driving shaft, another element iscontinuously connected to a receiving shaft and the two remainingelements are coupled together through the intermediary of the continuousspeedvarying device.

An arrangement of this kind makes it possible for the speedvaryingdevice to work under operating conditions which are less severe thanthose in which it would be placed if it were directly interposed betweenthe driving shaft and the receiving shaft. However, it does not resolvein an entirely satisfactory manner the problem of small overall size forthe speed-varying gear with an extended range of speed ratios for thetransmission.

The present invention has for its object a continuous transmissionbetween a movement take-off and a receiving shaft, especially forautomobile vehicles, comprising a continuous reversible speed-varyinggear preferably having a forward range and a reverse range, and aplanetary train with four elements of the family of the type described,which complies better than in the past with the various requirements ofpractice, in particular as regards the dimensioning of the speedvaryinggear, its life, the efficiency of the transmission and/or the extent ofthe speed ratios of the transmission.

The continuous transmission forming the object of the invention isespecially characterized in that two elements of the train are active ina continuous manner while being coupled, one to the movement take-offthrough the intermediary of the reversible continuous speed-varyinggear, the other to the receiving shaft, in that each of the tworemaining elements, known as the switching elements is adapted to bemade active or passive, and in that means are provided for making one ofthe said elements active while the other element is passive. or viceversa, so as to obtain operation of the transmission over at least tworanges for the purpose of increasing its performance.

These two ranges are preferably but not necessarily chosen to becontiguous in order to obtain continuity in the variation of the speedratios of the transmission between the lowest ratio and the highestratio. The planetary train is preferably chosen to be strictly orapproximately harmonic and/or symmetrical, as will be explained in adetailed manner below. When the ranges are not contiguous, there areobtained two ranges of continuous variation of ratios with a gap betweenthem.

In a first form of embodiment of the invention, each of the twochange-over elements is adapted, when it is placed in an activecondition, to be coupled to the movement take-off. With an arrangementof this kind, the maximum power passing into the speed-varying gear issubstantially reduced, which makes it possible to provide this latterwith reduced dimensions.

The coupling between each change-over element and the movement take-offmay be direct or alternatively it may comprise auxiliary means forimproving the performance, consisting of a box having two or moreratios, which makes it possible to multiply the possible combinations ofoperation. This box may be of any appropriate type.

in a second form of embodiment of the invention, one of the twochange-over elements is adapted, when it is placed in an activecondition, to be coupled to the movement take-off, while the otherchange-over element is adapted, when it is placed in an activecondition, to be coupled to the fixed frame. With such an arrangement,the extent of the speed ratios of the transmission is substantiallyincreased.

In this second form of embodiment of the invention, the change-overelement adapted, when it is placed in an active condition, to be coupledto the movement take-off, has an additional active condition in which itis coupled to the fixed frame, which provides the transmission withreverse operation in addition to forward operation.

Auxiliary means for further improving the performance of this secondform of embodiment of the invention may be provided, and comprise asecond gear train similar to that of the second form of embodiment ofthe invention and receiving as its continuous input, the output of thisgear train, and having two change-over elements of which one can becoupled to the movement take-off and the other to the fixed frame. lfnecessary, this arrangement can be repeated several times.

in a third form of embodiment'of the invention, two gear trains areprovided, the first similar to the first form of embodiment of theinvention, while the second, which is arranged in a manner similar tothat of the second form of embodiment, receives as its continuous inputthe output of the first, and has two change-over elements, one of whichcan be coupled to the movement take-off and the other to the fixedtrain. By virtue of this arrangement, the maximum power passing throughthe speed-varying gear is substantially reduced, which makes it possibleto give this latter smaller dimensions, while at the same time theextent of the speed ratios of the transmission is increased.

The performance of this third form of embodiment of the invention mayalso be further improved by the auxiliary means which have beenpreviously referred to and which are applicable to the first and/or thesecond gear train.

The objects, characteristic features and advantages of the inventionwill be further brought out in the description which follows below offorms of embodiment chosen by way of example, reference being made tothe accompanying drawings, in which:

FlG.1 is a diagram of a transmission in accordance with the invention;

FIG.2 is a diagrammatic view of this transmission in longitudinalsection;

FlG.3 shows diagrammatically the reversible continuous speed-varyinggear of the transmission shown in FIGSJ and 2;

FIG.4 is similar to FIG.1 and FIG.5 is similar to FIG.2, but relate toan alternative form;

FlG.6 6 is similar to FIG.1 and FIG.7 is similar to FlG.2 but relate tostill another alternative form.

Reference will first be made to FIGSJ to 3. A transmission between amovement take-off P and a receiving shaft R comprises a continuousreversible speed-varying gear V and a planetary train T with fourelements A, B, C, and D.

The continuous reversible speed-varying gear V may be of any appropriatetype which permits the establishment of a speed ratio and a torque ratiowhich are continuously variable between two shafts l and 1 1 (FIG.3)with transmission in either direction and providing a forward range anda reverse range. Such a speed-varying device V is for example of thehydraulic type shown in FIG.3, 3, comprising two units U and Uassociated respectively with the shafts and 11, each unit being eitherdriving or driven, the units U and U being coupled together by conduitsl2 and 13 with the interposition of a control device 14 which enablesthe speed and torque ratios of the shafts 10 and l l to be continuouslyregulated.

The planetary train T with four elements A, B, C, and D belongs to thefamily of the type described, and comprises, in the example of FIG.2,two single planetary gears coupled together. One of these planetaryportions has a planet-wheel 15, a crown-wheel 16 and a satellite carrier17, the satellites 18 of which engage with the planet-wheel and with thecrown-wheel 16. The other planetary portion has a planetwheel 19, acrown-wheel 20 and a satellite carrier 21, the satellites 22 of whichengage with the planet-wheel 19 and the crown-wheel 20. The satellitecarrier 17 is fixed to the crownwheel 20, while the crown-wheel 16 isfixed to the satellite carrier 21.

The first element A is constituted by 15; the second element B isconstituted by gear elements 17 and 20; the third element C is formed bygear elements 16 and 21, and the fourth element D is constituted by 19.

Referring to the various diagrams of FIGS], 4, 6, 7, 9 and 11, it willbe noted that in all cases the two elements of the train .A and C areactive continuously. The element A is coupled to the movement take-off Pthrough the intermediary of the speed-varying device V. The element C iscoupled to the receiving shaft R. The two remaining elements B and D,known as the change-over elements, are each adapted to be made active orpassive. The element B is active while the element D is passive and theelement B is passive while the element D is active. In this way, theoperation of the transmission has at least two ranges, contiguous orotherwise.

In the example of H651 to 3, each of the change-over elements B and D isadapted, when it is put into an active condition, to be coupled to themovement take-off P. This result is obtained by means oftwo clutches Eand E (FIGSJ and 2).

In more detail, the transmission of the example shown in F [68.1 to 3comprises a driving shaft 23 which is driven by a motor M and whichconstitutes the movement take-off P in this case. The clutch 5,, isinterposed between the shaft 23 and the satellite carrier 17 forming theelement B, while the clutch E is interposed between the shaft 23 and theplanet-wheel 19 forming the element D.

The clutches E and E are of the multi-disc type, for examle. p The shaft23 is coupled by a pair of pinions 24 and 25 to the shaft 10 of the unitU of the speed-varying device V. The shaft 11 of the unit U of the saidspeed-varying device V is coupled by a pair of pinions 26 and 27 to theplanet-wheel 15 which forms the element A.

The receiving shaft R which is fixed to the crown-wheel 21 forming theelement C is coupled by two pinions 28 and 29 and by adirection-reversing device 30 to the output shaft 31 of thetransmission. The reversing device 30 may be of any suitable type andcomprises for example a forward-running dog clutch 32 and a reversingdog-clutch 33.

In a first range of increasing ratios of the transmission, the unit U:of the speed-varying device B first operates over the reversing rangewith a reduction of the speed ratios of the speed-varying device V untilthis ratio is annulled, and then over the forward range with an increaseof the said speed ratio from zero up to a maximum. During this firstrange, the clutch E is engaged and the clutch E is released.

Over a second range of increasing transmission ratios, the unit U of thespeed-varying device V first continues to work on the forward range withreducing ratios of speeds of the speed-varying device V from thismaximum down to zero, and then works on the reverse range with increaseof the said ratios from zero up to a maximum, which may be equal to ordifferent in absolute value from the maximum of the first range. Duringthis second range, the clutch E,, is engaged and the clutch E isreleased.

By virtue of the arrangement which has just been described, the powerpassing into the speed-varying device V and which decreases as thetransmission ratio increases, has a maximum value considerably lowerthan the output of the motor. This enables the dimensions of thespeed-varying device V to be reduced and increases its life.

It will be appreciated that the two ranges of operation referred toabove are contiguous, which permits full use to be made of thespeed-varying device V.

At the junction point of the two contiguous ranges, the power relativeto the first range is the same as the power relative to the secondrange.

If m and m represent the respective basic or overall ratios of theportion 15, 16, 17, 18 and the portion 19, 20, 21, 22 of the gear trainT, namely:

number of teeth of the crown-wheel 16 number of teeth of theplanet-wheel 15 the equality of powers is expressed by the followingharmonic relation:

m m =l+m,+m (l) A gear train T which satisfies the relation (1) isdesignated in the present description by the term harmonic train.

It is also advantageous, especially for reasons of simplicity, to havethe following symmetrical relation:

A gear train T which satisfies the relation (2) is designated in thepresent description by the term symmetrical train.

The train T preferably satisfies both relations l and (2) at the sametime, and the basic ratio of such a symmetrical harmonic train is:

m=m =m =2.4l4 3 Good results have been obtained with a symmetricalharmonic train T, the pinions of which have the following numbers ofteeth:

Pinions 15 and 19: 34 teeth Crown-wheel 16 and 20: 83 teeth Satellites18 and 22: 24 teeth.

There is thus obtained a continuous transmission in which the ratio ofspeeds varies from 0.414 to 1.828 with a speedvarying device V, themaximum power of which only requires to be 41.4 percent of that of themotor.

Instead of the train T being strictly harmonic and/or symmetrical, itmay of course only satisfy the conditions (1) and/or (2) in anapproximate manner, at the same time per mitting excellent operation. Incase of need, it is possible to compensate such an approximation byconditioning in consequence the speed-varying device and/or thetransmission.

in the example of FIGSJ and 2, the elements B and D are coupled with thesame ratio to the movement take-ofi, but they could be connected theretowith different ratios.

Reference will now be made to FIGSA 4 and 5, in which the arrangement issimilar to that which has just been described with reference to F 105.1to 3, but in which an auxiliary means is provided. This auxiliary meansconsists for example of a gear-box G which is interposed between themovement takeoff P and the clutches E E which make it possible tomultiply the obtainable combinations of operation.

The gear-box G has for example two speed ratios: unity ratio obtained bya clutch 34 and a small ratio obtained by a brake 35.

By acting on the various parts E E 34, 35 and on the speed-varyingdevice V, it is possible to obtain for example a continuous transmissionin which the ratio of speeds between P and C (F105) is of the order of0.33 to 2.5 with a speedvarying device V, whose maximum power onlyrequires to be 33 percent of that of the motor.

Reference will now be made to FIGS.6 and 7, in which two trains T and Tare provided, the first similar to that of FIGJ with elements A, B, C,and D,'and the second with elements A, B, C, and D.

The element A is coupled to the movement take-ofi P through theintermediary of the speed-varying device V, while the element C is fixedto the element A.

The elements B and D are coupled respectively to the movement take-off Pby clutches E and E,, as in FlGJ, while the elements B and D are coupledrespectively on the one hand to the movement take-0E P by a clutch E tothe fixed frame by a brake F and on the other hand to the fixed frame bya brake F The element C constitutes the output ofthe transmission.

With an arrangement of this kind, the advantages of the arrangement ofFlG.l are accumulated, and there is obtained a transmission in which themaximum power passing through the speed-varying device is reduced andwhich has a large range of speed ratios.

More particularly, on forward running it is possible to obtain a ratioof speeds varying from 0.43 to 2.43 and for reverse running a ratio ofspeeds varying from 0.43 to 1.43, while using a speed-varying device Vhaving a maximum power which is 33 percent of that of the motor.

If necessary, other trains can be added to the sequence, such as forexample the train T indicated in broken lines at A", B", C", and D inFlG.6, in order to increase still further the range of speed ratios ofthe transmission.

The invention is not limited to the forms of embodiment described andillustrated, but includes all alternative forms.

What I claim is:

l. A continuous power transmission for use in motor vehicles arrangedbetween an input shaft and an output shaft, comprising a continuousspeed-varying device driven by said input shaft, a plurality ofplanetary gear trains each including a plurality of drivingly connectedgear elements providing parallel power paths of different ratio, one ofsaid planetary gear trains having a first element driven by saidspeed-varying device and a second element common to a first element ofanother of said planetary gear trains, said one planetary gear trainhaving a third element common to a second element of said anotherplanetary gear train and driving said output shaft, said anotherplanetary gear train having a third element, and control means forselectively coupling either of said first and third elements of saidanother planetary gear train to said input shaft.

2. A transmission as claimed in claim 1, said one planetary gear trainhaving an overall ratio m and said another planetary gear train havingan overall ratio m the following relationship being satisfied: m X m l mm 3. A transmission as claimed in claim 1, said one planetary gear trainhaving an overall ratio m and said another planetary gear train havingan overall ratio m. the following relationship being satisfied: m m

4. A transmission as claimed in claim 1, said one planetary gear trainhaving an overall ratio m and said another planetary gear train havingan overall ratio m the following relationships being satisfied:

m Xm l +m +m m,=m

5. A transmission as claimed in claim 1, having a fixed frame, and afurther planetary gear train between said third element of said oneplanetary gear train and said output shaft, said further planetary geartrain comprising a first element coupled to said third element of saidone planetary gear train, a second element adapted to be selectivelycoupled to the input shaft, a third element coupled to the output shaft,a fourth element adapted to be selectively coupled to said fixed frame,and control means for selectively coupling said second element of saidfurther train to the input shaft or making it free, and for selectivelycoupling said fourth element of said further train to said fixed frameor making it free.

6. A transmission as claimed in claim 5, the last-named control meansselectively coupling said second element of said further train to saidfixed frame.

7. A transmission as claimed in claim 1, and a gear box interposedbetween said input shaft and said control means.

1. A continuous power transmission for use in motor vehicles arrangedbetween an input shaft and an output shaft, comprising a continuousspeed-varying device driven by said input shaft, a plurality ofplanetary gear trains each including a plurality of drivingly connectedgear elements providing parallel power paths of different ratio, one ofsaid planetary gear trains having a first element driven by saidspeed-varying device and a second element common to a first element ofanother of said planetary gear trains, said one planetary gear trainhaving a third element common to a second element of said anotherplanetary gear train and driving said output shaft, said anotherplanetary gear train having a third element, and control means forselectively coupling either of said first and third elements of saidanother planetary gear train to said input shaft.
 2. A transmission asclaimed in claim 1, said one planetary gear train having an overallratio m1 and said another planetary gear train having an overall ratiom2, the following relationship being satisfied: m1 X m2 1 + m1 + m2. 3.A transmission as claimed in claim 1, said one planetary gear trainhaving an overall ratio m1 and said another planetary gear train havingan overall ratio m2, the following relationship being satisfied: m1 m2.4. A transmission as claimed in claim 1, said one planetary gear trainhaving an overall ratio m1 and said another planetary gear train havingan overall ratio m2, the following relationships being satisfied: m1 Xm2 1 + m1 + m2 : m1 m2.
 5. A transmission as claimed in claim 1, havinga fixed frame, and a further planetary gear train between said thirdelement of said one planetary gear train and said output shaft, saidfurther planetary gear train comprising a first element coupled to saidthird element of said one planetary gear train, a second element adaptedto be selectively coupled to the input shaft, a third element coupled tothe output shaft, a fourth element adapted to be selectively coupled tosaid fixed frame, and control means for selectively coupling said secondelement of said further train to the input shaft or making it free, andfor selectively coupling said fourth element of said further train tosaid fixed frame or making it free.
 6. A transmission as claimed inclaim 5, the last-named control means selectively coupling said secondelement of said further train to said fixed frame.
 7. A transmission asclaimed in claim 1, and a gear box interposed between said input shaftand said control means.